Rotary machine state observation device, rotary machine, and rotary machine state observation method

ABSTRACT

A state observation device ( 30 ) uses an ADC ( 37 ) to digitize a detection signal from a gap sensor ( 21 ) at a low-speed sampling period and uses a separation unit ( 38 ) to separate the digitized detection signal into vane detection signals considered to be for the detection of a vane of a compressor impeller and non-vane detection signals considered not to be for the detection of a vane. Further, the determination unit ( 39 ) extracts a vane peak detection signal considered to be for a vane peak by comparing a vane detection signal with vane detection signals corresponding to other vanes and non-vane detection signals, and a shaft vibration and tip clearance are determined as states of the compressor impeller on the basis of the extracted vane peak detection signal. Thus, the state observation device ( 30 ) is capable of observing the state of a rotary machine without carrying out high-speed sampling.

TECHNICAL FIELD

The present invention relates to a rotary machine state observationdevice, a rotary machine, and a rotary machine state observation method.

BACKGROUND ART

In a rotary machine such as a turbo machine, an impeller whichintegrally rotates with a rotor is provided. The impeller includes aplurality of vanes and is accommodated in a casing.

In addition, a predetermined amount of clearance is required between thevanes and the casing to reliably prevent contact between the vanes ofthe impeller and the casing.

However, during operation of the rotary machine, synchronous vibrationsdue to a rotation frequency of the rotor, backlash of a bearing portionwhich supports the rotor, non-synchronous vibrations due to turbulenceor the like of a flowing fluid, or the like may occur. Accordingly, thevanes oscillate beyond the clearance due to the vibrations and the vanesare likely to come into contact with the casing.

In view of the above, a state observation device disclosed in PTL 1 forobserving a state of a turbo machine measures a rotation speed of arotating body which is an impeller, shaft vibrations, and a tipclearance which is a gap between the rotating body and a casing by onesenor which outputs a signal synchronized with a rotation of therotating body, stores vibration amplitude, an amplification factor, andthe tip clearance for each rotation speed during an initial operation,and weights the vibration amplitude, the amplification factor, and thetip clearance. In addition, in a case these sums exceed a presetthreshold value, the state observation device determines that the stateof the turbo machine is in an abnormal state and issues a warning.

CITATION LIST Patent Literature

[PTL 1] Japanese Unexamined Patent Application Publication No.2013-224847

SUMMARY OF INVENTION Technical Problem

In the state observation device disclosed in PTL 1, since the rotatingbody rotates at a high speed and a vane passes through the sensor atvery short time intervals, for example, several microseconds, it isnecessary to perform digitalization on an output signal of the sensor byhigh-speed sampling.

In order to realize high-speed sampling, an analog-digital converterwhich can perform high-speed sampling with high frequencycharacteristics is required, which generates an increase in a cost ofthe entire device.

The present invention is made in consideration of the above-describedcircumstances, and an object thereof is to provide a rotary machinestate observation device, a rotary machine, and a rotary machine stateobservation method in which a state of the rotary machine can beobserved without performing high-speed sampling.

Solution to Problem

In order to achieve the object, a rotary machine state observationdevice, a rotary machine, and a rotary machine state observation methodof the present invention adopt the following means.

According to a first aspect of the present invention, there is provideda rotary machine state observation device, including: detection meansfor detecting a distance between an impeller of a rotary machine and thedetection means, the detection means being provided at an interval in aradial direction between the impeller and the detection means;conversion means for digitizing a detection signal detected by thedetection means at a predetermined sampling period; separation means forseparating a detection signal digitized by the conversion means into avane detection signal considered to be for detection of a vane of theimpeller and a non-vane detection signal considered not to be fordetection of the vane; and determination means for extracting a vanedetection signal considered to be for a peak of the vane by comparingthe vane detection signal with vane detection signals corresponding toother vanes and the non-vane detection signal and determining a state ofthe impeller on the basis of the extracted vane detection signal.

According to the present configuration, the detection means is providedat an interval in the radial direction between the impeller of therotary machine and the detection means, and the detection signaldetected by the detection means is digitized by the conversion means ata predetermined sampling period.

Here, for example, an impeller of a turbo machine or the like rotates ata high speed such as 3,000 rpm. Accordingly, in order to accuratelydetect the distance between the impeller and the detection means,preferably, the conversion means digitizes the detection signal byhigh-speed sampling. Here, the high-speed sampling is a sampling periodat which a peak of the vane can be clearly determined by performingsampling on one vane three times or more, for example. However, in orderto perform the high-speed sampling, conversion means having highperformance is required, or the like, which increases a cost.

Meanwhile, the detection signal is digitized for a non-high speedsampling period, for example, for a sampling period at which one vanecan be detected only once or twice, and accordingly, the conversionmeans having high performance is not required.

Therefore, in the present configuration, the separation means separatesthe detection signal digitized by the conversion means into a vanedetection signal considered to be for detection of the vane of theimpeller and a non-vane detection signal considered not to be fordetection of the vane. As an example of a separation method, a method ofseparating the detection signal using a predetermined threshold value isused.

However, if the detection signal is digitized at a sampling period whichis performed on one vane approximately once or twice, the digitized vanedetection signal does not necessarily indicate the peak of the vane, anda detection signal indicating a vane position deviated from the peak islikely to be digitized. In this way, in the vane detection signaldigitized at the non-high speed sampling period, a detection result withrespect to the peak of the vane and a detection result of the vaneposition deviated from the peak are mixed.

Accordingly, the determination means extracts a vane detection signalconsidered to be for a peak of the vane by comparing the vane detectionsignal with vane detection signals corresponding to other vanes and thenon-vane detection signal. For example, as a comparison method, there isa method of calculating a height of the vane from a difference betweeneach vane detection signal and the non-vane detection signal andextracting the vane detection signal considered to be for the peak ofthe vane on the basis of the height of the vane indicated by each vanedetection signal.

Moreover, the determination means determines the state of the impelleron the basis of the extracted vane detection signal considered to be forthe peak of the vane.

In this way, in the present configuration, by relatively comparing thevane detection signals of the plurality of vanes and the non-vanedetection signals, the vane detection signal considered to be for thepeak of the vane is extracted and the state of the impeller isdetermined. Accordingly, since it is enough for a detection signalindicating a distance to the vane to be sampled at least once for eachvane, in the present configuration, it is possible to observe the stateof the rotary machine without performing high-speed sampling.

In the first aspect, the determination means may less weight the vanedetection signal as a deviation amount from the vane detection signalindicating the highest value increases.

In the present configuration, with respect to the determination of thestate of the impeller, it is possible to decrease influences of the vanedetection signal having a large deviation amount from the peak.

In the first aspect, the predetermined sampling period may be determinedon the basis of a time interval at which one vane passes through aposition facing the detection means.

In the present configuration, as a non-high speed sampling period, it ispossible to determine an appropriate sampling period.

According to a second aspect of the present invention, there is provideda rotary machine, including: an impeller; a casing which accommodatesthe impeller; and the above-described state observation device.

According to a third aspect of the present invention, there is provideda rotary machine state observation method, including: a first step ofdetecting a distance between an impeller of a rotary machine anddetection means by the detection means which is provided at an intervalin a radial direction between the impeller and the detection means; asecond step of digitizing a detection signal detected by the detectionmeans at a predetermined sampling period; a third step of separating thedigitized detection signal into a vane detection signal considered to befor detection of a vane of the impeller and a non-vane detection signalconsidered not to be for detection of the vane; and a fourth step ofextracting a vane detection signal considered to be for a peak of thevane by comparing the vane detection signal with vane detection signalscorresponding to other vanes and the non-vane detection signal anddetermining a state of the impeller on the basis of the extracted vanedetection signal.

Advantageous Effects of Invention

According to the present invention, it is possible to observe the stateof the rotary machine without performing high-speed sampling.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a configuration view of a turbocharger according an embodimentof the present invention.

FIG. 2 is a configuration view of a vane according to the embodiment ofthe present invention.

FIG. 3 is a block diagram showing an electrical configuration of a stateobservation device according to the embodiment of the present invention.

FIG. 4 is a schematic diagram showing a detection signal of a gap sensoraccording to the embodiment of the present invention.

FIG. 5 is a schematic diagram showing an example of low-speed samplingaccording to the embodiment of the present invention.

FIG. 6 is a schematic diagram showing an example of a vane detectionposition by the low-speed sampling according to the embodiment of thepresent invention.

FIG. 7 is a flowchart showing a flow of impeller state determinationprocessing according to the embodiment of the present invention.

FIG. 8 is a flowchart showing a flow of shaft vibration determinationprocessing according to the embodiment of the present invention.

FIG. 9 is flowchart showing a flow of tip clearance determinationprocessing according to the embodiment of the present invention.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments of a rotary machine state observation device, arotary machine, and a rotary machine state observation method accordingto the present invention will be described with reference to thedrawings.

FIG. 1 is a configuration view of a turbocharger 1 according to thepresent embodiment.

As shown in FIG. 1, the turbocharger 1 includes a turbine 2 whichconverts energy of an exhaust gas E of an engine into a rotation and acompressor 11 which is driven by the turbine 2.

The compressor 11 compresses suctioned air W to generate compressed airPW and forcibly feeds the compressed air PW to the engine.

The turbine 2 is configured of a turbine body 3, and a turbine casing 4which covers the turbine body 3 from the outer peripheral side andincludes an inlet passage 5 and an outlet passage 6 of the exhaust gasE.

The turbine body 3 includes stator vanes 7 which are attached to theturbine casing 4 and rotor vanes 8 which are attached to a disk 9 whichrotates about an axis P.

The stator vanes 7 are provided to protrude from the turbine casing 4 tothe inside in the radial direction of the axis P on a connection portionbetween the inlet passage 5 and the outlet passage 6, and a plurality ofstator vanes 7 are disposed at intervals in a peripheral direction ofthe axis P.

The rotor vanes 8 are provided to protrude from an outer peripheralsurface of the disk 9 toward the outside in the radial direction and aredisposed between the stator vanes 7 at predetermined intervals on adownstream side (a left side on a paper surface of FIG. 1) of the statorvane 7.

The compressor 11 includes a compressor impeller 12 which is a rotatingbody which is rotatable about the axis P, and a compressor casing 14which covers the compressor impeller 12 from the outer periphery.

The compressor impeller 12 is a centrifugal impeller which includes aplurality of vanes 13. As shown in FIG. 2, the vanes 13 are provided atpredetermined intervals in the peripheral direction of the axis P, andfor example, 11 vanes 13 are provided.

The compressor casing 14 includes an air inlet 15 through which the airW is suctioned and an outlet scroll 16 which discharges the compressedair PW compressed by the compressor impeller 12.

In addition, the compressor impeller 12 and the disk 9 are fitted to arotor 17 which rotates about the axis P and integrally rotate about theaxis P with each other. In addition, the rotor 17 is rotatably supportedabout the axis P by two radial bearings 18 and one thrust bearing 19.

In addition, as shown in FIG. 2, a gap sensor 21 is provided in thecompressor casing 14. The gap sensor 21 is provided in the compressorcasing 14 at a position facing the vanes 13 of the compressor impeller12 and measures a distance to a shroud side tip of the vanes 13.

For example, the gap sensor 21 according to the present embodiment is anon-contact displacement meter which uses an eddy current effect. Inaddition, for example, only one gap sensor 21 is provided in thecompressor casing 14, and the gap sensor 21 is positioned at the sameposition as the inner peripheral surface of the compressor casing 14(refer to FIG. 6).

Here, an operation principle of the displacement meter which uses theeddy current effect will be described. The displacement meter isconfigured of a coil which generates a high frequency magnetic flux, anddetects a change of an eddy current generated on the surface of the vane13 which is a measurement target as a change of impedance of the coil bya high frequency magnetic flux generated from the coil. That is, thechange of the distance according to the passage of the vane 13 isdetected by the change of the impedance of the coil, and the maximumoutput is obtained when the vane 13 is closest.

FIG. 3 is a block diagram showing an electrical configuration of a stateobservation device 30 according to the present embodiment.

The state observation device 30 includes the above-described gap sensor21, a conversion unit 31, an analog signal processing unit 32, and adigital signal processing unit 33. In addition, the state observationdevice 30 acquires three values, that is, a rotation speed of thecompressor impeller 12, a vibration of the compressor impeller 12, and aclearance between the compressor impeller and the compressor casing 14based on the detection signal of the gap sensor 21, and determines thestate of the compressor impeller 12.

Here, the detection signal (analog signal) output from the gap sensor 21will be described with reference to FIG. 4. In FIG. 4, a horizontaldirection indicates time, and a vertical direction indicates amplitude.

As shown in FIG. 4, when the gap sensor 21 faces each vane 13, the gapsensor 21 outputs a larger detection signal as a distance between thegap sensor 21 and the compressor impeller 12 decreases. That is, thedetection signal which is periodically output from the gap sensor 21 hasa waveform (solid line in FIG. 4) which has large amplitude when eachvane 13 and the gap sensor 21 face each other and small amplitude at aposition at which each vane 13 and the gap sensor 21 are separated fromeach other, specifically, at an intermediate point between adjacentvanes 13.

In addition, every time the compressor impeller 12 rotates once, peakshaving the number of times (in the present embodiment, 11 times, and N1to N11) corresponding to the number of vanes 13 are output from the gapsensor 21.

The detection signal indicated by the solid in FIG. 4 is output from thegap sensor 21 to the conversion unit 31.

For example, the conversion unit 31 includes an amplifier circuit whichuses a transistor or the like, amplifies weak detection signals from thegap sensor 21, and outputs the amplified detection signals to the analogsignal processing unit 32 and the digital signal processing unit 33.

The analog signal processing unit 32 includes a frequency division unit35 and a rotation speed calculation unit 36.

The detection signal (analog signal) of the gap sensor 21 amplified bythe conversion unit 31 is input to the frequency division unit 35, andthe frequency division unit 35 divides the detection signal by apredetermined number of times (in the present embodiment, 11 times whichis the same as the number of vanes 13) and outputs a rotation speedsignal synchronized with the rotation speed of the compressor impeller12.

The rotation speed calculation unit 36 counts the number of the rotationspeed signals from the frequency division unit 35 so as to calculate therotation speed of the compressor impeller 12.

The digital signal processing unit 33 includes an analog-digitalconvertor (hereinafter, referred to as “ADC”) 37, a separation unit 38,and a determination unit 39.

The ADC 37 converts the detection signal output from the gap sensor 21from an analog signal to a digital signal at a predetermined samplingperiod. For example, in FIG. 4, broken lines indicate samplingintervals, and black dots on an analog waveform indicate detectionsignals sampled by the ADC 37.

The separation unit 38 separates the detection signal digitalized by theADC 37 into a vane detection signal considered to be for detection ofthe vane 13 and a non-vane detection signal considered not to be fordetection of the vane 13. In addition, the non-vane detection signal isa detection signal which is generated by detecting the rotor 17 or theroot of the vane 13 instead of the vane 13.

A threshold value A shown FIG. 4 is for separating the vane detectionsignal and the non-vane detection signal, and the detection signal equalto or more than the threshold value A is separated as the vane detectionsignal and the detection signal less than the threshold value A isseparated as the non-vane detection signal by the separation unit 38.

The determination unit 39 extracting a vane detection signal consideredto be for a peak (hereinafter, referred to as a “vane peak”) of the vane13 by relatively comparing the vane detection signal with vane detectionsignals with respect to other vanes 13 and the non-vane detection signaland determines the state of the compressor impeller 12 on the basis ofthe extracted vane detection signal.

The determination unit 39 includes an extraction unit which performs theextraction, a shaft vibration determination unit 41, and a tip clearancedetermination unit 42.

The shaft vibration determination unit 41 determines the vibration stateof the compressor impeller 12.

The tip clearance determination unit 42 determines a state of aclearance (refer to FIG. 4) between the maximum value of the vane peakof the compressor impeller 12 and an inner peripheral surface of thecompressor casing 14.

In addition, for example, the separation unit 38 and the determinationunit 39 included in the digital signal processing unit 33 are configuredof a Central Processing Unit (CPU), a Random Access Memory (RAM), a ReadOnly Memory (ROM), a computer readable storage medium, or the like. Inaddition, for example, a series of processing of realizing variousfunctions is stored in a storage medium or the like in the form of aprogram, the CPU causes the RAM or the like to read out the program toperform information processing/calculation, and the various functionsare realized. In addition, the program may be installed in a ROM orother storage mediums in advance, may be provided in a state of beingstored in a computer readable storage medium, or may be distributed viawired or wireless communication means. The computer readable storagemedium is a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM,a semiconductor memory, or the like.

Here, for example, the compressor impeller 12 rotates at a high speedsuch as 3,000 rpm. Accordingly, in order to accurately detect thedistance between the compressor impeller 12 and the compressor casing14, preferably, the ADC digitizes the detection signal at high-speedsampling. Here, the high-speed sampling is a sampling period at which apeak of the vane can be clearly determined by performing sampling on onevane 13 three times or more, for example. However, in order to performthe high-speed sampling, the ADC having high performance is required, orthe like, which increases a cost.

Accordingly, in the state observation device 30 according to the presentembodiment, the detection signal is digitized for a non-high speedsampling period, for example, for a sampling period (hereinafter,referred to as “low-speed sampling”) at which one vane 13 can bedetected only once or twice, and accordingly, the ADC having highperformance is not required.

The sampling period by the ADC 37 according to the present embodiment isdetermined on the basis of the time interval at which one vane 13 passesthrough a position facing the gap sensor 21.

The following Expressions (1) to (4) are examples of calculationexpressions for determining the low-sampling period by the ADC 37according to the present embodiment.

$\begin{matrix}{\lbrack {{Expression}\mspace{14mu} 1} \rbrack \mspace{596mu}} & \; \\{V = {\frac{D}{2} \times \omega}} & (1) \\{\lbrack {{Expression}\mspace{14mu} 2} \rbrack \mspace{596mu}} & \; \\{V = {\frac{D}{2} \times ( {2 \times \pi \times \frac{N}{60}} )}} & (2) \\{\lbrack {{Expression}\mspace{14mu} 3} \rbrack \mspace{596mu}} & \; \\{F = ( {\pi \times \frac{D}{n \cdot V}} )^{- 1}} & (3) \\{\lbrack {{Expression}\mspace{14mu} 4} \rbrack \mspace{596mu}} & \; \\{{Fs} = {10 \times F}} & (4)\end{matrix}$

Expressions (1) and (2) are calculation expressions with respect to aperipheral speed V (m/s) of a tip portion of the vane 13, D is an outerperipheral diameter (m) of the compressor impeller 12 corresponding toan installation position of the gap sensor 21, ω is an angular velocity(rad/s), and N is a rotation speed (rpm) of the compressor impeller 12.In addition, o is converted like Expression (2) using the rotation speedN (rpm) of the compressor impeller 12.

In addition, Expression (3) is a calculation expression with respect toa frequency F (Hz, hereinafter, referred to as an “inter-vane passfrequency”) at which one vane 13 passes through the gap sensor 21 and nis the number of vanes 13.

In addition, Fs is a sampling frequency (Hz), and in the presentembodiment, for example, as shown in Expression (4), Fs is 10 times theinter-vane pass frequency F.

Here, for example, in a case where the diameter D is 35 mm, the number nof the vanes 13 is 11, and the rotation speed N is 28,000 rpm, theperipheral speed V of the tip portion is 51.3 m/s, the inter-vane passfrequency F is 5,100 Hz, and the sampling frequency Fs is 51 kHz.Accordingly, it is possible to sample the vane peak by setting thesampling frequency of ADC 37 to 50 kHz.

FIG. 5 shows an example of the low-speed sampling. Black dots on awaveform shown in FIG. 5 indicate examples of the detection signalssampled by the ADC 37 according to the present embodiment. As shown inFIG. 5, 10 detection signals (v1 to v10) can be sampled by the low-speedsampling with respect to the waveform showing each vane 13 and itssurroundings. Among the detection signals, two (v2 and v3) exceed thethreshold value A and are vane detection signals indicating the vane 13.In addition, since the detection signals v1 and v4 to v9 are less thanthe threshold value A, the detection signals v1 and v4 to v9 arenon-vane detection signals.

However, if the detection signal is digitized by the low-speed sampling,the digitized vane detection signal does not necessarily indicate thevane peak, and a detection signal indicating a vane position deviatedfrom the vane peak is likely to be digitized.

That is, it is preferable to sample the detection signal indicating thevane peak. However, in the low-speed sampling, like the detection withrespect to the vane 13 shown by a broken line in FIG. 6, the detectionsignal in which the center (also referred to as an abdominal) of thevane 13 is detected is likely to be sampled.

In this way, if the state of the compressor impeller 12 is determined ina state where the vane detection signal considered not to be for thevane peak is included, the determination is likely to be erroneouslyperformed.

Accordingly, the extraction unit 40 included in the determination unit39 compares each vane detection signal with vane detection signalscorresponding to other vanes 13 and the non-vane detection signal, andextracts a vane detection signal (hereinafter, referred to as a “vanepeak detection signal”) considered to be for a vane peak.

For example, in a comparison method performed by the extraction unit 40,a difference between the vane detection signal and the non-vanedetection signal is calculated for each vane detection signal as aheight (hereinafter, referred to as a “vane height”) of the vane 13, andthe vane peak detection signal is extracted on the basis of the vaneheight indicated by each vane detection signal. Meanwhile, sincedetection frequency with respect to the non-vane detection signalincreases, the number of times of the non-vane detection signals is notcounted. By not counting the non-vane detection signals, erroneousdetermination is not performed.

For example, as a calculation method of the vane height, there is amethod of setting a difference between the lowest value of the non-vanedetection signal and each vane detection signal to the vane height ofthe vane detection signal or a method of setting a difference between anaverage value of the non-vane detection signals and each vane detectionsignal to the vane height of each vane detection signal.

In addition, the extraction unit 40 according to the present embodimentweights the vane detection signal when extracting the vane peakdetection signal. Specifically, less weighting is applied to the vanedetection signal as a deviation amount from the vane detection signalindicating the highest vane height increases.

The weighting will be described with reference to FIG. 4.

As shown on the right side of the paper surface in FIG. 4, theextraction unit 40 obtains the number of times for each value (vaneheight) indicated by the vane detection signal and for each valueindicated by the non-vane detection signal, which are performed by aplurality of times of sampling. The extraction unit 40 determines aweighting factor such that the highest value of the vane detectionsignal becomes the greatest weight and the lowest value of the vanedetection signal becomes the smallest weight, on the basis of the numberof times.

That is, since the compressor impeller 12 rotates while being slightlyvibrates, even when the vane detection signal detects the vane peak,variations in the size occur (amplitude of the vane peak shown by abroken line in FIG. 4). Accordingly, there is a case where it is notclear whether the vane detection signal having a small vane height isthe detection result of the vane peak or is the detection result of theabdominal of the vane 13. Accordingly, the number of times (frequency)of the value of the vane height is obtained, a weighting factor for eachvalue of the vane detection signal is determined on the basis of thenumber of times, and the determined weighting factor is multiplied bythe value of each vane detection signal.

That is, it is considered that the vane detection signals correspondingto the value of the maximum number of times and the value larger thanthe maximum number of times indicate the vane peak. Accordingly, as avane detection signal is smaller than the value of the maximum number oftimes, a possibility that the vane detection signal does not indicatethe vane peak is higher. In order to clarifying this relationship,weighting is applied to the vane detection signal, and extraction of thevane peak detection signal is easily performed.

Moreover, as described above, the weighting factor is determined suchthat the highest value of the vane detection signal becomes maximum andthe lowest value of the vane detection signal becomes minimum. However,the weighting factor is determined such that a difference between theweight corresponding to the value of the maximum number of times and theweight corresponding to the highest value decreases and a differencebetween the weight corresponding to the value of the maximum number oftimes and the weight corresponding to the lowest value increases.

In addition, for example, the extraction unit 40 does not consider thevane detection signal in which the value to which the weighting factoris multiplied is equal to or less than a predetermined threshold valueas the vane peak detection signal, and extracts the vane detectionsignal exceeding the threshold value as the vane peak detection signal.

In the example of FIG. 4, the vane detection signal with respect to thevane 13 of N1 is a detection signal which is considered to not bedetection for the vane peak.

FIG. 7 is a flowchart showing a flow of impeller state determinationprocessing according to the present embodiment performed by the digitalsignal processing unit 33.

First, in Step 100, the detection signal output from the gap sensor 21is converted from an analog signal into a digital signal at low-speedsampling by the ADC 37.

Next, in Step 102, a predetermined number of the detection signalsrequired for performing a state determination of the compressor impeller12 are subjected to low-speed sampling, and the sampled detectionsignals are stored in the store means. For example, here, thepredetermined number is a number corresponding to one rotation of thecompressor impeller 12, and in the present embodiment, is 11.

Next, in Step 104, whether or not the predetermined number of detectionsignals is sampled is determined, and in a case of an affirmativedetermination, the process proceeds to Step 106. Meanwhile, in a case ofa negative determination, the process returns to Step 100, and Steps 100and 102 are repeated until the predetermined number of detection signalsis sampled.

In Step 106, the separation unit 38 separates a vane detection signalv_(n) from the detection signal subjected to low-speed sampling.

Next, in Step S108, based on the value (vane height) indicated by thevane detection signal v_(n) and the number of times for each vane heightindicated by the vane detection signal v_(n), the weighting factor w_(n)for each vane detection signal v_(n) is determined.

Next, in Step 110, the vane detection signal v_(n) is multiplied by thecorresponding weight factor w_(n).

Next, in Step S112, the vane peak detection signal is extracted from thevane detection signal v_(n) multiplied by the weighting factor w_(n).

Moreover, the processing of Steps 108 to 112 is performed by theextraction unit 40.

Next, in Step 114, based on the extracted vane peak detection signal,the shaft vibration determination unit 41 performs shaft vibrationdetermination processing, the tip clearance determination unit 42performs the tip clearance determination processing, and the state ofthe compressor impeller 12 is determined.

Moreover, after this determination ends, the processing returns to Step100, and the impeller state determination processing is performed on thebasis of the detection signal which is newly subjected to low-speedsampling.

FIG. 8 is a flowchart showing a flow of the shaft vibrationdetermination processing according to the present embodiment performedby the shaft vibration determination unit 41.

First, in Step 200, the maximum value vmax and the minimum value vmin ofthe vane peak detection signal are derived.

Next, in Step 202, a difference between the maximum value vmax and theminimum value vmin of the vane peak detection signal is calculated as avibration component A_(n).

Next, in Step 204, the vibration component A_(n) and a predeterminedreference vibration component AA are compared with each other, whetheror not the vibration component A_(n) exceeds the reference vibrationcomponent AA is determined, and in a case of the affirmativedetermination, the process proceeds to Step 206. Meanwhile, in a casewhere the vibration component A_(n) does not exceed the referencevibration component AA, the shaft vibration determination processingends, and the process returns to Step 100.

The reference vibration component AA is a threshold value for detectingabnormal vibrations of the rotary machine, and if the vibrationcomponent A_(n) reaches the reference vibration component AA, forexample, notification of alarm or automatic stop of the rotary machineis performed. That is, the reference vibration component AA is an alarmsetting value or an automatic stop setting value of the rotary machine.In addition, a plurality of reference vibration components AA differentfrom each other may be set, and every time the vibration component Anincreases and reaches the plurality of reference vibration componentsAA, notification of alarm or automatic stop of the rotary machine may beperformed in stages.

In Step 206, the shaft vibration is excessive, and notification ofwarning is performed. Accordingly, a worker stops an apparatus includingthe turbocharger 1 or repairs the turbocharger 1 when the turbocharger 1is inspected next time.

FIG. 9 is flowchart showing a flow of the tip clearance determinationprocessing according to the present embodiment performed by the tipclearance determination unit 42.

First, in Step 300, the maximum value vmax of the vane peak detectionsignal is derived. The maximum value v_(max) is a clearance B_(n)corresponding to the tip clearance.

Next, in Step 302, the clearance B_(n) and a predetermined referenceclearance BB are compared with each other, whether or not the clearanceB_(n) exceeds the reference clearance BB is determined, and in a case ofthe affirmative determination, the process proceeds to Step 304.Meanwhile, in a case where the clearance B_(n) does not exceed thereference clearance BB, the tip clearance determination processing ends,and the process returns to Step 100.

The reference clearance BB is a threshold value for detecting the vane13 approaching the compressor casing 14, and if the clearance B_(n)reaches the reference clearance BB, for example, notification of alarmor automatic stop of the rotary machine is performed. That is, thereference clearance BB is an alarm setting value or an automatic stopsetting value of the rotary machine. In addition, a plurality ofreference clearances BB different from each other may be set, and everytime the clearance B_(n) increases and reaches the plurality ofreference clearances BB, notification of alarm or automatic stop of therotary machine may be performed in stages.

In Step 304, notification of warning is performed in a case where thereis a possibility that the vane 13 comes into contact with the compressorcasing 14. Accordingly, a worker stops an apparatus including theturbocharger 1 or repairs the turbocharger 1 when the turbocharger 1 isinspected next time.

As described above, the state observation device 30 according to thepresent embodiment observes the rotation speed of the compressorimpeller 12 using the gap senor 21 which detects the distance betweenthe compressor impeller 12 and the gap sensor 21.

In addition, in the state observation device 30, the detection signal isdigitized by the gap sensor 21 at the low-speed sampling periodperformed by the ADC 37, and the digitized detection signal is separatedinto the vane detection signal considered to be for detection of thevane 13 of the compressor impeller 12 and the non-vane detection signalconsidered not to be for detection of the vane 13 by the separation unit38. In addition, the vane detection signal and the vane detectionsignals corresponding to other vanes 13 and the non-vane detectionsignal are compared with each other by the determination unit 39, thevane peak detection signal considered to be for the vane peak isextracted, and the shaft vibration and the tip clearance which arestates of the compressor impeller 12 are determined on the basis of theextracted vane peak detection signal.

In this way, in the state observation device 30 according the presentembodiment, the vane detection signals and the non-vane detectionsignals of the plurality of vanes 13 are relatively compared with eachother, the vane peak detection signal considered to be for the vane peakis extracted, and the state of the compressor impeller 12 is determined.Accordingly, since it is enough for the detection signal indicating thedistance to the vane 13 to be sampled at least once for each vane 13, tothe state observation device 30 can observe the state of theturbocharger 1 without performing high-speed sampling.

Hereinbefore, the present invention is described with reference theabove-described embodiment. However, a technical scope of the presentinvention is not limited to the range described in the embodiment.Various modifications or improvements can be applied to the embodimentwithin a scope which does not depart from the gist of the presentinvention, and the aspects to which the modifications or theimprovements are added also are included in the technical scope of thepresent invention. In addition, the above-described embodiments may beappropriately combined.

For example, in the above-described embodiment, the aspect in which onegap sensor 21 is provided in the compressor casing 14 is described.However, the present invention is not limited to this, and an aspect inwhich a plurality of gap sensors 21 are provided at positions at whichthe phases are deviated from each other may be adopted.

For example, in the above-described embodiment, the aspect in which therotary machine according to the present invention is the turbocharger 1is described. However, the present invention is not limited to this, andother rotary machines may be adopted as long as the rotary machineincludes the impeller.

In addition, the flow of each processing described in theabove-described embodiment is an example, an unnecessary step may beomitted, a new step may be added, or a processing sequence may bereplaced within a scope which does not depart from the gist of thepresent invention.

REFERENCE SIGNS LIST

1: turbocharger

12: compressor impeller

21: gap sensor

30: state observation device

37: analog-digital convertor (ADC)

38: separation unit

39: determination unit

40: extraction unit

1. A rotary machine state observation device, comprising: detectionmeans for detecting a distance between an impeller of a rotary machineand the detection means, the detection means being provided at aninterval in a radial direction between the impeller and the detectionmeans; conversion means for digitizing a detection signal detected bythe detection means at a predetermined sampling period; separation meansfor separating a detection signal digitized by the conversion means intoa vane detection signal considered to be for detection of a vane of theimpeller and a non-vane detection signal considered not to be fordetection of the vane; and determination means for extracting a vanedetection signal considered to be for a peak of the vane by comparingthe vane detection signal with vane detection signals corresponding toother vanes and the non-vane detection signal and determining a state ofthe impeller on the basis of the extracted vane detection signal.
 2. Therotary machine state observation device according to claim 1, whereinthe determination means less weights the vane detection signal as adeviation amount from the vane detection signal indicating the highestvalue increases.
 3. The rotary machine state observation deviceaccording to claim 1, wherein the predetermined sampling period isdetermined on the basis of a time interval at which one vane passesthrough a position facing the detection means.
 4. A rotary machine,comprising: an impeller; a casing which accommodates the impeller; andthe state observation device according to claim
 1. 5. A rotary machinestate observation method, comprising: a first step of detecting adistance between an impeller of a rotary machine and detection means bythe detection means which is provided at an interval in a radialdirection between the impeller and the detection means; a second step ofdigitizing a detection signal detected by the detection means at apredetermined sampling period; a third step of separating the digitizeddetection signal into a vane detection signal considered to be fordetection of a vane of the impeller and a non-vane detection signalconsidered not to be for detection of the vane; and a fourth step ofextracting a vane detection signal considered to be for a peak of thevane by comparing the vane detection signal with vane detection signalscorresponding to other vanes and the non-vane detection signal anddetermining a state of the impeller on the basis of the extracted vanedetection signal.